services/surfaceflinger/Scheduler/VSyncReactor.cpp - android_frameworks_native - Gitiles

 /*
  * Copyright 2019 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #define ATRACE_TAG ATRACE_TAG_GRAPHICS
 #undef LOG_TAG
 #define LOG_TAG "VSyncReactor"
 //#define LOG_NDEBUG 0
 #include "VSyncReactor.h"
 #include <cutils/properties.h>
 #include <log/log.h>
 #include <utils/Trace.h>
 #include "../TracedOrdinal.h"
 #include "TimeKeeper.h"
 #include "VSyncDispatch.h"
 #include "VSyncTracker.h"

 namespace android::scheduler {
 using base::StringAppendF;

 Clock::~Clock() = default;
 nsecs_t SystemClock::now() const {
     return systemTime(SYSTEM_TIME_MONOTONIC);
 }

 class PredictedVsyncTracer {
 public:
     PredictedVsyncTracer(VSyncDispatch& dispatch)
           : mRegistration(dispatch,
                           std::bind(&PredictedVsyncTracer::callback, this, std::placeholders::_1,
                                     std::placeholders::_2),
                           "PredictedVsyncTracer") {
         mRegistration.schedule(0, 0);
     }

 private:
     TracedOrdinal<bool> mParity = {"VSYNC-predicted", 0};
     VSyncCallbackRegistration mRegistration;

     void callback(nsecs_t /*vsyncTime*/, nsecs_t /*targetWakeupTim*/) {
         mParity = !mParity;
         mRegistration.schedule(0, 0);
     }
 };

 VSyncReactor::VSyncReactor(std::unique_ptr<Clock> clock, std::unique_ptr<VSyncDispatch> dispatch,
                            std::unique_ptr<VSyncTracker> tracker, size_t pendingFenceLimit,
                            bool supportKernelIdleTimer)
       : mClock(std::move(clock)),
         mTracker(std::move(tracker)),
         mDispatch(std::move(dispatch)),
         mPendingLimit(pendingFenceLimit),
         mPredictedVsyncTracer(property_get_bool("debug.sf.show_predicted_vsync", false)
                                       ? std::make_unique<PredictedVsyncTracer>(*mDispatch)
                                       : nullptr),
         mSupportKernelIdleTimer(supportKernelIdleTimer) {}

 VSyncReactor::~VSyncReactor() = default;

 // The DispSync interface has a 'repeat this callback at rate' semantic. This object adapts
 // VSyncDispatch's individually-scheduled callbacks so as to meet DispSync's existing semantic
 // for now.
 class CallbackRepeater {
 public:
     CallbackRepeater(VSyncDispatch& dispatch, DispSync::Callback* cb, const char* name,
                      nsecs_t period, nsecs_t offset, nsecs_t notBefore)
           : mName(name),
             mCallback(cb),
             mRegistration(dispatch,
                           std::bind(&CallbackRepeater::callback, this, std::placeholders::_1,
                                     std::placeholders::_2),
                           mName),
             mPeriod(period),
             mOffset(offset),
             mLastCallTime(notBefore) {}

     ~CallbackRepeater() {
         std::lock_guard<std::mutex> lk(mMutex);
         mRegistration.cancel();
     }

     void start(nsecs_t offset) {
         std::lock_guard<std::mutex> lk(mMutex);
         mStopped = false;
         mOffset = offset;

         auto const schedule_result = mRegistration.schedule(calculateWorkload(), mLastCallTime);
         LOG_ALWAYS_FATAL_IF((schedule_result != ScheduleResult::Scheduled),
                             "Error scheduling callback: rc %X", schedule_result);
     }

     void setPeriod(nsecs_t period) {
         std::lock_guard<std::mutex> lk(mMutex);
         if (period == mPeriod) {
             return;
         }
         mPeriod = period;
     }

     void stop() {
         std::lock_guard<std::mutex> lk(mMutex);
         LOG_ALWAYS_FATAL_IF(mStopped, "DispSyncInterface misuse: callback already stopped");
         mStopped = true;
         mRegistration.cancel();
     }

     void dump(std::string& result) const {
         std::lock_guard<std::mutex> lk(mMutex);
         StringAppendF(&result, "\t%s: mPeriod=%.2f last vsync time %.2fms relative to now (%s)\n",
                       mName.c_str(), mPeriod / 1e6f, (mLastCallTime - systemTime()) / 1e6f,
                       mStopped ? "stopped" : "running");
     }

 private:
     void callback(nsecs_t vsynctime, nsecs_t wakeupTime) {
         {
             std::lock_guard<std::mutex> lk(mMutex);
             mLastCallTime = vsynctime;
         }

         mCallback->onDispSyncEvent(wakeupTime, vsynctime);

         {
             std::lock_guard<std::mutex> lk(mMutex);
             if (mStopped) {
                 return;
             }
             auto const schedule_result = mRegistration.schedule(calculateWorkload(), vsynctime);
             LOG_ALWAYS_FATAL_IF((schedule_result != ScheduleResult::Scheduled),
                                 "Error rescheduling callback: rc %X", schedule_result);
         }
     }

     // DispSync offsets are defined as time after the vsync before presentation.
     // VSyncReactor workloads are defined as time before the intended presentation vsync.
     // Note change in sign between the two defnitions.
     nsecs_t calculateWorkload() REQUIRES(mMutex) { return mPeriod - mOffset; }

     const std::string mName;
     DispSync::Callback* const mCallback;

     std::mutex mutable mMutex;
     VSyncCallbackRegistration mRegistration GUARDED_BY(mMutex);
     bool mStopped GUARDED_BY(mMutex) = false;
     nsecs_t mPeriod GUARDED_BY(mMutex);
     nsecs_t mOffset GUARDED_BY(mMutex);
     nsecs_t mLastCallTime GUARDED_BY(mMutex);
 };

 bool VSyncReactor::addPresentFence(const std::shared_ptr<FenceTime>& fence) {
     if (!fence) {
         return false;
     }

     nsecs_t const signalTime = fence->getCachedSignalTime();
     if (signalTime == Fence::SIGNAL_TIME_INVALID) {
         return true;
     }

     std::lock_guard<std::mutex> lk(mMutex);
     if (mExternalIgnoreFences || mInternalIgnoreFences) {
         return true;
     }

     bool timestampAccepted = true;
     for (auto it = mUnfiredFences.begin(); it != mUnfiredFences.end();) {
         auto const time = (*it)->getCachedSignalTime();
         if (time == Fence::SIGNAL_TIME_PENDING) {
             it++;
         } else if (time == Fence::SIGNAL_TIME_INVALID) {
             it = mUnfiredFences.erase(it);
         } else {
             timestampAccepted &= mTracker->addVsyncTimestamp(time);

             it = mUnfiredFences.erase(it);
         }
     }

     if (signalTime == Fence::SIGNAL_TIME_PENDING) {
         if (mPendingLimit == mUnfiredFences.size()) {
             mUnfiredFences.erase(mUnfiredFences.begin());
         }
         mUnfiredFences.push_back(fence);
     } else {
         timestampAccepted &= mTracker->addVsyncTimestamp(signalTime);
     }

     if (!timestampAccepted) {
         mMoreSamplesNeeded = true;
         setIgnorePresentFencesInternal(true);
         mPeriodConfirmationInProgress = true;
     }

     return mMoreSamplesNeeded;
 }

 void VSyncReactor::setIgnorePresentFences(bool ignoration) {
     std::lock_guard<std::mutex> lk(mMutex);
     mExternalIgnoreFences = ignoration;
     updateIgnorePresentFencesInternal();
 }

 void VSyncReactor::setIgnorePresentFencesInternal(bool ignoration) {
     mInternalIgnoreFences = ignoration;
     updateIgnorePresentFencesInternal();
 }

 void VSyncReactor::updateIgnorePresentFencesInternal() {
     if (mExternalIgnoreFences || mInternalIgnoreFences) {
         mUnfiredFences.clear();
     }
 }

 nsecs_t VSyncReactor::computeNextRefresh(int periodOffset, nsecs_t now) const {
     auto const currentPeriod = periodOffset ? mTracker->currentPeriod() : 0;
     return mTracker->nextAnticipatedVSyncTimeFrom(now + periodOffset * currentPeriod);
 }

 nsecs_t VSyncReactor::expectedPresentTime(nsecs_t now) {
     return mTracker->nextAnticipatedVSyncTimeFrom(now);
 }

 void VSyncReactor::startPeriodTransition(nsecs_t newPeriod) {
     ATRACE_CALL();
     mPeriodConfirmationInProgress = true;
     mPeriodTransitioningTo = newPeriod;
     mMoreSamplesNeeded = true;
     setIgnorePresentFencesInternal(true);
 }

 void VSyncReactor::endPeriodTransition() {
     ATRACE_CALL();
     mPeriodTransitioningTo.reset();
     mPeriodConfirmationInProgress = false;
     mLastHwVsync.reset();
 }

 void VSyncReactor::setPeriod(nsecs_t period) {
     ATRACE_INT64("VSR-setPeriod", period);
     std::lock_guard lk(mMutex);
     mLastHwVsync.reset();

     if (!mSupportKernelIdleTimer && period == getPeriod()) {
         endPeriodTransition();
         setIgnorePresentFencesInternal(false);
         mMoreSamplesNeeded = false;
     } else {
         startPeriodTransition(period);
     }
 }

 nsecs_t VSyncReactor::getPeriod() {
     return mTracker->currentPeriod();
 }

 void VSyncReactor::beginResync() {
     mTracker->resetModel();
 }

 void VSyncReactor::endResync() {}

 bool VSyncReactor::periodConfirmed(nsecs_t vsync_timestamp, std::optional<nsecs_t> HwcVsyncPeriod) {
     if (!mPeriodConfirmationInProgress) {
         return false;
     }

     if (!mLastHwVsync && !HwcVsyncPeriod) {
         return false;
     }

     const bool periodIsChanging =
             mPeriodTransitioningTo && (*mPeriodTransitioningTo != getPeriod());
     if (mSupportKernelIdleTimer && !periodIsChanging) {
         // Clear out the Composer-provided period and use the allowance logic below
         HwcVsyncPeriod = {};
     }

     auto const period = mPeriodTransitioningTo ? *mPeriodTransitioningTo : getPeriod();
     static constexpr int allowancePercent = 10;
     static constexpr std::ratio<allowancePercent, 100> allowancePercentRatio;
     auto const allowance = period * allowancePercentRatio.num / allowancePercentRatio.den;
     if (HwcVsyncPeriod) {
         return std::abs(*HwcVsyncPeriod - period) < allowance;
     }

     auto const distance = vsync_timestamp - *mLastHwVsync;
     return std::abs(distance - period) < allowance;
 }

 bool VSyncReactor::addResyncSample(nsecs_t timestamp, std::optional<nsecs_t> hwcVsyncPeriod,
                                    bool* periodFlushed) {
     assert(periodFlushed);

     std::lock_guard<std::mutex> lk(mMutex);
     if (periodConfirmed(timestamp, hwcVsyncPeriod)) {
         ATRACE_NAME("VSR: period confirmed");
         if (mPeriodTransitioningTo) {
             mTracker->setPeriod(*mPeriodTransitioningTo);
             for (auto& entry : mCallbacks) {
                 entry.second->setPeriod(*mPeriodTransitioningTo);
             }
             *periodFlushed = true;
         }

         if (mLastHwVsync) {
             mTracker->addVsyncTimestamp(*mLastHwVsync);
         }
         mTracker->addVsyncTimestamp(timestamp);

         endPeriodTransition();
         mMoreSamplesNeeded = mTracker->needsMoreSamples();
     } else if (mPeriodConfirmationInProgress) {
         ATRACE_NAME("VSR: still confirming period");
         mLastHwVsync = timestamp;
         mMoreSamplesNeeded = true;
         *periodFlushed = false;
     } else {
         ATRACE_NAME("VSR: adding sample");
         *periodFlushed = false;
         mTracker->addVsyncTimestamp(timestamp);
         mMoreSamplesNeeded = mTracker->needsMoreSamples();
     }

     if (!mMoreSamplesNeeded) {
         setIgnorePresentFencesInternal(false);
     }
     return mMoreSamplesNeeded;
 }

 status_t VSyncReactor::addEventListener(const char* name, nsecs_t phase,
                                         DispSync::Callback* callback,
                                         nsecs_t /* lastCallbackTime */) {
     std::lock_guard<std::mutex> lk(mMutex);
     auto it = mCallbacks.find(callback);
     if (it == mCallbacks.end()) {
         // TODO (b/146557561): resolve lastCallbackTime semantics in DispSync i/f.
         static auto constexpr maxListeners = 4;
         if (mCallbacks.size() >= maxListeners) {
             ALOGE("callback %s not added, exceeded callback limit of %i (currently %zu)", name,
                   maxListeners, mCallbacks.size());
             return NO_MEMORY;
         }

         auto const period = mTracker->currentPeriod();
         auto repeater = std::make_unique<CallbackRepeater>(*mDispatch, callback, name, period,
                                                            phase, mClock->now());
         it = mCallbacks.emplace(std::pair(callback, std::move(repeater))).first;
     }

     it->second->start(phase);
     return NO_ERROR;
 }

 status_t VSyncReactor::removeEventListener(DispSync::Callback* callback,
                                            nsecs_t* /* outLastCallback */) {
     std::lock_guard<std::mutex> lk(mMutex);
     auto const it = mCallbacks.find(callback);
     LOG_ALWAYS_FATAL_IF(it == mCallbacks.end(), "callback %p not registered", callback);

     it->second->stop();
     return NO_ERROR;
 }

 status_t VSyncReactor::changePhaseOffset(DispSync::Callback* callback, nsecs_t phase) {
     std::lock_guard<std::mutex> lk(mMutex);
     auto const it = mCallbacks.find(callback);
     LOG_ALWAYS_FATAL_IF(it == mCallbacks.end(), "callback was %p not registered", callback);

     it->second->start(phase);
     return NO_ERROR;
 }

 void VSyncReactor::dump(std::string& result) const {
     std::lock_guard<std::mutex> lk(mMutex);
     StringAppendF(&result, "VsyncReactor in use\n");
     StringAppendF(&result, "Has %zu unfired fences\n", mUnfiredFences.size());
     StringAppendF(&result, "mInternalIgnoreFences=%d mExternalIgnoreFences=%d\n",
                   mInternalIgnoreFences, mExternalIgnoreFences);
     StringAppendF(&result, "mMoreSamplesNeeded=%d mPeriodConfirmationInProgress=%d\n",
                   mMoreSamplesNeeded, mPeriodConfirmationInProgress);
     if (mPeriodTransitioningTo) {
         StringAppendF(&result, "mPeriodTransitioningTo=%" PRId64 "\n", *mPeriodTransitioningTo);
     } else {
         StringAppendF(&result, "mPeriodTransitioningTo=nullptr\n");
     }

     if (mLastHwVsync) {
         StringAppendF(&result, "Last HW vsync was %.2fms ago\n",
                       (mClock->now() - *mLastHwVsync) / 1e6f);
     } else {
         StringAppendF(&result, "No Last HW vsync\n");
     }

     StringAppendF(&result, "CallbackRepeaters:\n");
     for (const auto& [callback, repeater] : mCallbacks) {
         repeater->dump(result);
     }

     StringAppendF(&result, "VSyncTracker:\n");
     mTracker->dump(result);
     StringAppendF(&result, "VSyncDispatch:\n");
     mDispatch->dump(result);
 }

 void VSyncReactor::reset() {}

 } // namespace android::scheduler
	/*
	* Copyright 2019 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#define ATRACE_TAG ATRACE_TAG_GRAPHICS
	#undef LOG_TAG
	#define LOG_TAG "VSyncReactor"
	//#define LOG_NDEBUG 0
	#include "VSyncReactor.h"
	#include <cutils/properties.h>
	#include <log/log.h>
	#include <utils/Trace.h>
	#include "../TracedOrdinal.h"
	#include "TimeKeeper.h"
	#include "VSyncDispatch.h"
	#include "VSyncTracker.h"

	namespace android::scheduler {
	using base::StringAppendF;

	Clock::~Clock() = default;
	nsecs_t SystemClock::now() const {
	return systemTime(SYSTEM_TIME_MONOTONIC);
	}

	class PredictedVsyncTracer {
	public:
	PredictedVsyncTracer(VSyncDispatch& dispatch)
	: mRegistration(dispatch,
	std::bind(&PredictedVsyncTracer::callback, this, std::placeholders::_1,
	std::placeholders::_2),
	"PredictedVsyncTracer") {
	mRegistration.schedule(0, 0);
	}

	private:
	TracedOrdinal<bool> mParity = {"VSYNC-predicted", 0};
	VSyncCallbackRegistration mRegistration;

	void callback(nsecs_t /vsyncTime/, nsecs_t /targetWakeupTim/) {
	mParity = !mParity;
	mRegistration.schedule(0, 0);
	}
	};

	VSyncReactor::VSyncReactor(std::unique_ptr<Clock> clock, std::unique_ptr<VSyncDispatch> dispatch,
	std::unique_ptr<VSyncTracker> tracker, size_t pendingFenceLimit,
	bool supportKernelIdleTimer)
	: mClock(std::move(clock)),
	mTracker(std::move(tracker)),
	mDispatch(std::move(dispatch)),
	mPendingLimit(pendingFenceLimit),
	mPredictedVsyncTracer(property_get_bool("debug.sf.show_predicted_vsync", false)
	? std::make_unique<PredictedVsyncTracer>(*mDispatch)
	: nullptr),
	mSupportKernelIdleTimer(supportKernelIdleTimer) {}

	VSyncReactor::~VSyncReactor() = default;

	// The DispSync interface has a 'repeat this callback at rate' semantic. This object adapts
	// VSyncDispatch's individually-scheduled callbacks so as to meet DispSync's existing semantic
	// for now.
	class CallbackRepeater {
	public:
	CallbackRepeater(VSyncDispatch& dispatch, DispSync::Callback* cb, const char* name,
	nsecs_t period, nsecs_t offset, nsecs_t notBefore)
	: mName(name),
	mCallback(cb),
	mRegistration(dispatch,
	std::bind(&CallbackRepeater::callback, this, std::placeholders::_1,
	std::placeholders::_2),
	mName),
	mPeriod(period),
	mOffset(offset),
	mLastCallTime(notBefore) {}

	~CallbackRepeater() {
	std::lock_guard<std::mutex> lk(mMutex);
	mRegistration.cancel();
	}

	void start(nsecs_t offset) {
	std::lock_guard<std::mutex> lk(mMutex);
	mStopped = false;
	mOffset = offset;

	auto const schedule_result = mRegistration.schedule(calculateWorkload(), mLastCallTime);
	LOG_ALWAYS_FATAL_IF((schedule_result != ScheduleResult::Scheduled),
	"Error scheduling callback: rc %X", schedule_result);
	}

	void setPeriod(nsecs_t period) {
	std::lock_guard<std::mutex> lk(mMutex);
	if (period == mPeriod) {
	return;
	}
	mPeriod = period;
	}

	void stop() {
	std::lock_guard<std::mutex> lk(mMutex);
	LOG_ALWAYS_FATAL_IF(mStopped, "DispSyncInterface misuse: callback already stopped");
	mStopped = true;
	mRegistration.cancel();
	}

	void dump(std::string& result) const {
	std::lock_guard<std::mutex> lk(mMutex);
	StringAppendF(&result, "\t%s: mPeriod=%.2f last vsync time %.2fms relative to now (%s)\n",
	mName.c_str(), mPeriod / 1e6f, (mLastCallTime - systemTime()) / 1e6f,
	mStopped ? "stopped" : "running");
	}

	private:
	void callback(nsecs_t vsynctime, nsecs_t wakeupTime) {
	{
	std::lock_guard<std::mutex> lk(mMutex);
	mLastCallTime = vsynctime;
	}

	mCallback->onDispSyncEvent(wakeupTime, vsynctime);

	{
	std::lock_guard<std::mutex> lk(mMutex);
	if (mStopped) {
	return;
	}
	auto const schedule_result = mRegistration.schedule(calculateWorkload(), vsynctime);
	LOG_ALWAYS_FATAL_IF((schedule_result != ScheduleResult::Scheduled),
	"Error rescheduling callback: rc %X", schedule_result);
	}
	}

	// DispSync offsets are defined as time after the vsync before presentation.
	// VSyncReactor workloads are defined as time before the intended presentation vsync.
	// Note change in sign between the two defnitions.
	nsecs_t calculateWorkload() REQUIRES(mMutex) { return mPeriod - mOffset; }

	const std::string mName;
	DispSync::Callback* const mCallback;

	std::mutex mutable mMutex;
	VSyncCallbackRegistration mRegistration GUARDED_BY(mMutex);
	bool mStopped GUARDED_BY(mMutex) = false;
	nsecs_t mPeriod GUARDED_BY(mMutex);
	nsecs_t mOffset GUARDED_BY(mMutex);
	nsecs_t mLastCallTime GUARDED_BY(mMutex);
	};

	bool VSyncReactor::addPresentFence(const std::shared_ptr<FenceTime>& fence) {
	if (!fence) {
	return false;
	}

	nsecs_t const signalTime = fence->getCachedSignalTime();
	if (signalTime == Fence::SIGNAL_TIME_INVALID) {
	return true;
	}

	std::lock_guard<std::mutex> lk(mMutex);
	if (mExternalIgnoreFences \|\| mInternalIgnoreFences) {
	return true;
	}

	bool timestampAccepted = true;
	for (auto it = mUnfiredFences.begin(); it != mUnfiredFences.end();) {
	auto const time = (*it)->getCachedSignalTime();
	if (time == Fence::SIGNAL_TIME_PENDING) {
	it++;
	} else if (time == Fence::SIGNAL_TIME_INVALID) {
	it = mUnfiredFences.erase(it);
	} else {
	timestampAccepted &= mTracker->addVsyncTimestamp(time);

	it = mUnfiredFences.erase(it);
	}
	}

	if (signalTime == Fence::SIGNAL_TIME_PENDING) {
	if (mPendingLimit == mUnfiredFences.size()) {
	mUnfiredFences.erase(mUnfiredFences.begin());
	}
	mUnfiredFences.push_back(fence);
	} else {
	timestampAccepted &= mTracker->addVsyncTimestamp(signalTime);
	}

	if (!timestampAccepted) {
	mMoreSamplesNeeded = true;
	setIgnorePresentFencesInternal(true);
	mPeriodConfirmationInProgress = true;
	}

	return mMoreSamplesNeeded;
	}

	void VSyncReactor::setIgnorePresentFences(bool ignoration) {
	std::lock_guard<std::mutex> lk(mMutex);
	mExternalIgnoreFences = ignoration;
	updateIgnorePresentFencesInternal();
	}

	void VSyncReactor::setIgnorePresentFencesInternal(bool ignoration) {
	mInternalIgnoreFences = ignoration;
	updateIgnorePresentFencesInternal();
	}

	void VSyncReactor::updateIgnorePresentFencesInternal() {
	if (mExternalIgnoreFences \|\| mInternalIgnoreFences) {
	mUnfiredFences.clear();
	}
	}

	nsecs_t VSyncReactor::computeNextRefresh(int periodOffset, nsecs_t now) const {
	auto const currentPeriod = periodOffset ? mTracker->currentPeriod() : 0;
	return mTracker->nextAnticipatedVSyncTimeFrom(now + periodOffset * currentPeriod);
	}

	nsecs_t VSyncReactor::expectedPresentTime(nsecs_t now) {
	return mTracker->nextAnticipatedVSyncTimeFrom(now);
	}

	void VSyncReactor::startPeriodTransition(nsecs_t newPeriod) {
	ATRACE_CALL();
	mPeriodConfirmationInProgress = true;
	mPeriodTransitioningTo = newPeriod;
	mMoreSamplesNeeded = true;
	setIgnorePresentFencesInternal(true);
	}

	void VSyncReactor::endPeriodTransition() {
	ATRACE_CALL();
	mPeriodTransitioningTo.reset();
	mPeriodConfirmationInProgress = false;
	mLastHwVsync.reset();
	}

	void VSyncReactor::setPeriod(nsecs_t period) {
	ATRACE_INT64("VSR-setPeriod", period);
	std::lock_guard lk(mMutex);
	mLastHwVsync.reset();

	if (!mSupportKernelIdleTimer && period == getPeriod()) {
	endPeriodTransition();
	setIgnorePresentFencesInternal(false);
	mMoreSamplesNeeded = false;
	} else {
	startPeriodTransition(period);
	}
	}

	nsecs_t VSyncReactor::getPeriod() {
	return mTracker->currentPeriod();
	}

	void VSyncReactor::beginResync() {
	mTracker->resetModel();
	}

	void VSyncReactor::endResync() {}

	bool VSyncReactor::periodConfirmed(nsecs_t vsync_timestamp, std::optional<nsecs_t> HwcVsyncPeriod) {
	if (!mPeriodConfirmationInProgress) {
	return false;
	}

	if (!mLastHwVsync && !HwcVsyncPeriod) {
	return false;
	}

	const bool periodIsChanging =
	mPeriodTransitioningTo && (*mPeriodTransitioningTo != getPeriod());
	if (mSupportKernelIdleTimer && !periodIsChanging) {
	// Clear out the Composer-provided period and use the allowance logic below
	HwcVsyncPeriod = {};
	}

	auto const period = mPeriodTransitioningTo ? *mPeriodTransitioningTo : getPeriod();
	static constexpr int allowancePercent = 10;
	static constexpr std::ratio<allowancePercent, 100> allowancePercentRatio;
	auto const allowance = period * allowancePercentRatio.num / allowancePercentRatio.den;
	if (HwcVsyncPeriod) {
	return std::abs(*HwcVsyncPeriod - period) < allowance;
	}

	auto const distance = vsync_timestamp - *mLastHwVsync;
	return std::abs(distance - period) < allowance;
	}

	bool VSyncReactor::addResyncSample(nsecs_t timestamp, std::optional<nsecs_t> hwcVsyncPeriod,
	bool* periodFlushed) {
	assert(periodFlushed);

	std::lock_guard<std::mutex> lk(mMutex);
	if (periodConfirmed(timestamp, hwcVsyncPeriod)) {
	ATRACE_NAME("VSR: period confirmed");
	if (mPeriodTransitioningTo) {
	mTracker->setPeriod(*mPeriodTransitioningTo);
	for (auto& entry : mCallbacks) {
	entry.second->setPeriod(*mPeriodTransitioningTo);
	}
	*periodFlushed = true;
	}

	if (mLastHwVsync) {
	mTracker->addVsyncTimestamp(*mLastHwVsync);
	}
	mTracker->addVsyncTimestamp(timestamp);

	endPeriodTransition();
	mMoreSamplesNeeded = mTracker->needsMoreSamples();
	} else if (mPeriodConfirmationInProgress) {
	ATRACE_NAME("VSR: still confirming period");
	mLastHwVsync = timestamp;
	mMoreSamplesNeeded = true;
	*periodFlushed = false;
	} else {
	ATRACE_NAME("VSR: adding sample");
	*periodFlushed = false;
	mTracker->addVsyncTimestamp(timestamp);
	mMoreSamplesNeeded = mTracker->needsMoreSamples();
	}

	if (!mMoreSamplesNeeded) {
	setIgnorePresentFencesInternal(false);
	}
	return mMoreSamplesNeeded;
	}

	status_t VSyncReactor::addEventListener(const char* name, nsecs_t phase,
	DispSync::Callback* callback,
	nsecs_t /* lastCallbackTime */) {
	std::lock_guard<std::mutex> lk(mMutex);
	auto it = mCallbacks.find(callback);
	if (it == mCallbacks.end()) {
	// TODO (b/146557561): resolve lastCallbackTime semantics in DispSync i/f.
	static auto constexpr maxListeners = 4;
	if (mCallbacks.size() >= maxListeners) {
	ALOGE("callback %s not added, exceeded callback limit of %i (currently %zu)", name,
	maxListeners, mCallbacks.size());
	return NO_MEMORY;
	}

	auto const period = mTracker->currentPeriod();
	auto repeater = std::make_unique<CallbackRepeater>(*mDispatch, callback, name, period,
	phase, mClock->now());
	it = mCallbacks.emplace(std::pair(callback, std::move(repeater))).first;
	}

	it->second->start(phase);
	return NO_ERROR;
	}

	status_t VSyncReactor::removeEventListener(DispSync::Callback* callback,
	nsecs_t* /* outLastCallback */) {
	std::lock_guard<std::mutex> lk(mMutex);
	auto const it = mCallbacks.find(callback);
	LOG_ALWAYS_FATAL_IF(it == mCallbacks.end(), "callback %p not registered", callback);

	it->second->stop();
	return NO_ERROR;
	}

	status_t VSyncReactor::changePhaseOffset(DispSync::Callback* callback, nsecs_t phase) {
	std::lock_guard<std::mutex> lk(mMutex);
	auto const it = mCallbacks.find(callback);
	LOG_ALWAYS_FATAL_IF(it == mCallbacks.end(), "callback was %p not registered", callback);

	it->second->start(phase);
	return NO_ERROR;
	}

	void VSyncReactor::dump(std::string& result) const {
	std::lock_guard<std::mutex> lk(mMutex);
	StringAppendF(&result, "VsyncReactor in use\n");
	StringAppendF(&result, "Has %zu unfired fences\n", mUnfiredFences.size());
	StringAppendF(&result, "mInternalIgnoreFences=%d mExternalIgnoreFences=%d\n",
	mInternalIgnoreFences, mExternalIgnoreFences);
	StringAppendF(&result, "mMoreSamplesNeeded=%d mPeriodConfirmationInProgress=%d\n",
	mMoreSamplesNeeded, mPeriodConfirmationInProgress);
	if (mPeriodTransitioningTo) {
	StringAppendF(&result, "mPeriodTransitioningTo=%" PRId64 "\n", *mPeriodTransitioningTo);
	} else {
	StringAppendF(&result, "mPeriodTransitioningTo=nullptr\n");
	}

	if (mLastHwVsync) {
	StringAppendF(&result, "Last HW vsync was %.2fms ago\n",
	(mClock->now() - *mLastHwVsync) / 1e6f);
	} else {
	StringAppendF(&result, "No Last HW vsync\n");
	}

	StringAppendF(&result, "CallbackRepeaters:\n");
	for (const auto& [callback, repeater] : mCallbacks) {
	repeater->dump(result);
	}

	StringAppendF(&result, "VSyncTracker:\n");
	mTracker->dump(result);
	StringAppendF(&result, "VSyncDispatch:\n");
	mDispatch->dump(result);
	}

	void VSyncReactor::reset() {}

	} // namespace android::scheduler